A proofing system is an apparatus used to generate a relatively limited number of copies of print simulations to verify that the copies are up to specifications in terms of color, quality, scaling, etc. A variety of color proofing systems have been developed to emulate offset printing results. Separately, other systems with different image formation characteristics have been created to emulate rotogravure printing results. These two types of systems vary fundamentally in that the first type needs to print copies composed of variable size dots of equal ink density, whereas the latter type must produce continuous tone reproductions made up of dots which vary both in size and in density.
Since in modern color scanners and page composition installations most of the data bases exist in digital form, some considerable thought has been given to producing digital color proofing systems which can lay down the types of dot patterns which most closely resemble the image structure of the desired prints, whether they be offset prints of gravure prints. Indeed, a few systems of this kind are now on the market. Unfortunately, however, they do not emulate the two required image structures closely enough. Also, the systems are extremely complex, very slow and costly. Even so, none of them can even produce a color print on a plain sheet of press paper such as used by printers. In other words, the printed sheets produced by such systems either exist as photographic film, or feature multiple layer laminates, or they are made of a special sheet of plain paper which is subsequently overcoated with a transparentizing varnish to fix the image. This varnishing step, unfortunately, alters the appearance of the paper.